player: remove extremely obscure undefined behavior

Apparently the value of a pointer is "indeterminate" after a free()
call, even if you never dereference the pointer after the free. Since
talloc_free() calls free(), this applies here.
video: removed unused stuff
manpage: document vf_vdpaupp
manpage: deprecated vo_vdpau postprocessing options

This seems a bit silly, but the way vf_vdpaupp works, this is cleaner.
manpage: adjust description of vdpau deint sub-option
client API: fix inverted condition

Oops. Sigh.